A modified COMFA model for elderly people in outdoor environments

Abstract

Older people are more vulnerable to heat-related discomforts and health issues due to age-induced changes in thermoregulatory mechanisms. To investigate the thermophysiological characteristics of older adults, we modified the COMFA model by measuring thermal physiological parameters and thermal sensations of 215 healthy elderly adults (>60 years) participating in different activities (sitting, walking and dancing). Our results demonstrated that: 1) the mean resting metabolic rate for the elderly was 37.2 W/m2 (males) and 36.1 W/m2 (females), respectively; 2) Correcting core temperature (Tc) and evaporative heat loss through perspiration, each 38.46 W/m2 increase in metabolic heat production responding to a 0.1 °C increase in Tc. Evaporative heat loss primarily depended on the maximum evaporative heat loss in hot environments; 3) percent body fat, age, and metabolic rate were significantly associated with body tissue resistance, and 4) the COMFA model overestimated the EB values in hot environments; the most serious overestimation was found with sedentary activities (45.24 W/m2). The modified COMFA-Senior model could effectively describe the differences caused by physiological parameters changes (RMSE = 9.5 W/m2) and better explained the changes in heat balance and actual thermal sensation during sitting and walking (R2 = 0.71 and 0.77), but could not describe that in dancing (R2 = 0.29).